


At Your Service

by bananab1tch



Category: Undertale (Video Game)
Genre: Abuse of italics, Crossdressing, Gaster came back after Asriel broke the barrier, Halloween Costumes, Light Dom/sub, M/M, Papyrus is not innocent, Pining, Plot What Plot/Porn Without Plot, Post-Canon, Post-Undertale Pacifist Route, Rough Oral Sex, W. D. Gaster is not related to Skelebros
Language: English
Status: Completed
Published: 2019-11-02
Updated: 2019-11-02
Packaged: 2021-01-18 18:15:20
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,917
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21281105
Author URL: https://archiveofourown.org/users/bananab1tch/pseuds/bananab1tch
Summary: It's Halloween on the surface and Undyne and Alphys have invited some friends over for a small party.One of those friends is Gaster, who is having a swell time all things considered, until Papyrus arrives.Wearing a maid's outfit.
Relationships: W. D. Gaster/Papyrus
Comments: 7
Kudos: 27





	At Your Service

"Who's ready to get **FUCKED UP**?!!?" screamed Undyne.

"Undyne, _language_," Toriel lightly scolded, tilting her head to Frisk sitting beside her, wearing a creeper costume and munching on candy.

It was Halloween and everyone had gathered at Undyne and Alphys' new house up on the surface. It was a relatively small party in house party standards, but there were still enough attendees for it to feel more than cozy. Invited were the hostesses, Toriel and Frisk, Asgore (who unfortunately couldn't make it due to being held up with a political meeting), some older members of the Royal Guard, and the skeleton brothers Sans and Papyrus.

One other invite, however, was their newest friend (who everyone seemed to remember the moment they laid eyes on him, but previously had no idea who the man was) was Gaster, one of the old directors of the science lab and co-creators of the Core.

The party was just beginning, with everyone but Sans and Papyrus having arrived. Gaster sat on the corner of one of the couches. He was wearing a mafia boss-like costume, since it was easy to find the materials for. He simply threw on a fancy pinstripe suit he had in his closet and a bowler hat he picked up from the store a day prior. The skeleton sipped his small glass of wine as he attempted to make small talk with Toriel.

"So how has life been adjusting on the surface?" asked Toriel, with Frisk now climbing on her lap. Despite the goat monster being clad in a witch's costume, she still gave off a warm and welcome presence that made it easy for anyone to speak to her.

"Oh, it's been a bit of a struggle, but over the past 9 months, everything has been moving along quite smoothly. My team of scientists have been making more strides to incorporate the core's type of energy into more surface buildings," he replied.Gaster had to admit he was quite proud of the work he had been doing up on the surface. Added with the fact that he was making a difference, the pay certainly more than compensated for all the hard work that went into his job.

"Oh, that's wonderful! Frisk and I have been a bit less busy than we initially had been when we all arrived on the surface, but we, including Asgore, have still been speaking to world leaders about the advancements for monster kind." Frisk looked up from their small snack and enthusiastically shook their head and signed, "_It's been nice to have more free time._"

"That's good, you three certainly have been making great progress," replied Gaster.

"Thank you so much. Say, how have Sans and Papyrus been? I head from Sans that they recently got jobs at your facility," questioned Toriel.

Indeed they did. Gaster had hired Sans not too long ago to be his secondhand. This decision was relatively easy, since he had been the shorter's boss back in the underground. Sans was a very smart individual and someone nice to have around, and Gaster was happy to be working with the skeleton again.

Papyrus, however, was someone he wasn't expecting to hire. One day at the lab Papyrus was visiting Sans during his lunch break when one of the machines sprung a leak. Sans went to fetch Gaster, but when the two scientists had arrived back, they found Papyrus underneath the machine, tightening up a loose metal plate.

Sans had originally panicked, begging Papyrus to get out from under there as Papyrus shouted, "OH DON'T WORRY BROTHER, I JUST NEED TO TIGHTEN ONE MORE SCREW!" while Gaster watched in amusement. Later that week Gaster has purposely disassembled a medium sized gadget and had asked Papyrus to reassemble it. Within half an hour, it was fixed and, to Gaster's surprise, seemed to work even better than before.

So, Gaster offered Papyrus the job in the engineering department of the laboratory, which Papyrus enthusiastically agreed too.

"Those two are such a delight. They're doing absolutely excellent work. I'm proud of both of them," answered Gaster.

Because of their now close quarters, Gaster had the opportunity to not only spend more time with Sans, but he also got to know his brother better as well. Papyrus was a ball of sunshine that always managed to pull Gaster in, and never failed to make him grin. Gaster began to enjoy almost everything about Papyrus. His words, his smile, his jaw, his arms, his _hips_…

Gaster caught himself. Yes, fine he may have an interest that was slightly a bit more inappropriate than a boss should have for his employees, but those feelings never had to be brought to light.

"Oh! Speak of the devil," gasped Toriel as the two turned to see Sans and Papyrus enter through the doors of the house.

"You twerps! Why are you two so late!" shouted Undyne as she ran to bring Papyrus into a huge embrace.

"PLEASE DON'T NOOGIE THE SKELETON."

"sorry fishsticks. to be fair, it was mostly me. took a nap that went on a little longer than expected."

On having a look of the skeletons, Gaster's mouth went agape.

Sans was wearing a black and purple jester's outfit, along with a ruffled yellow-green collar, but that's not what drew his attention.

What caught his eye was _Papyrus_.

Papyrus stood wearing a tight fit maid's outfit. It was the classic black and white color scheme with frills that cut much shorter down then they should have. He wore black thigh high stockings with a lacy design near the top. On _very_ close inspection, however, Gaster could see a hint of a garterbelt trailing up his dress connecting his tights to something underneath the skirt. Papyrus also wore lacy white gloves on his hands, making them seem more delicate.

Gaster's face flushed a deep purple and he tried to pry his gaze from Papyrus, but the way his figure exemplified itself in that costume…

"Hey P-Papyrus, thats a, uh, u-unique cost-tume??" Alphys commented once she looked over to Papyrus.

Upon Alphys' words Undyne gave Papyrus another look and her eyebrows flew to the top of her head. "Whoa dude! Didn't expect you to be the _type_," she exclaimed, lowering her voice and wiggling her eyebrows at the skeleton while saying the last words.

Papyrus scoffed. "HONESTLY UNDYNE, YOU CAN BE QUITE CHILDISH SOMETIMES. THE GREAT PAPYRUS JUST DECIDED, WHY GIVE UP AN AMAZING LOOK FOR A COSTUME? I'VE DECIDED TO DRESS UP AS A MAID TO EXEMPLIFY MY DUALITY!" he yelled proudly.

" 'm bro's right. besides, doesn't he look great?" Sans added, shifting his gaze slightly to Gaster, who was still on the couch. Gaster quickly broke the look, worried Sans had caught him staring.

"Why of course he does! It was just a bit of a surprise is all," said Toriel.

Smiling, Papyrus proclaimed, "WELL, NOW THAT WE ARE DONE ADMIRING MY COSTUME, LET'S GET BACK TO THE PARTY!"

With that, Gaster let his gaze break away from the tall skeleton. He stared down at his wine glass and took another sip, attempting to avoid eye contact with Papyrus.

He had a feeling he was going to be needing a lot more wine that night.

____________________

About 2 hours had passed and the party was going smoothly. Well, whatever the word "smoothly" meant to the individual.

They had played many party games like Monopoly (which promptly ended with Undyne flipping over the table), Uno (which promptly ended with Alphys glaring daggers into the winner), and even Candyland (which promptly ended with Frisk crushing their piece in silent frustration in losing 4 times in a row). Gaster had won the monopoly game, and when he did, he noticed Papyrus giving him a small smile. Strange, as it differed from his usually large grin.

The party had reached a bit of a dip with everyone engaging in casual conversation. Gaster brought his hand to take a gulp of his wine, but when he sucked in he was met with nothing but air. Looking down, Gaster realized that his glass was empty. Shuffling from his newest idle position, a corner near some of the dogs, he traversed his way to the kitchen to refill his glass.

He arrived inside the kitchen. The room was empty of other monsters. On the counters there were a wide variety of chips, cheeses and other snacks. Next to them were bottles of soda and juice, alongside what Gaster was looking for. He walked towards the glass and opened it to pour its contents into his cup.

Gaster nearly dropped the bottle from his hands when he felt a tap on his shoulder.

"GASTER, IS THERE ANY MORE LEFT?"

Turning to look behind him, Gaster was met with none other than Papyrus, looking at him quizzically. Gaster fought to keep the heat from rising into his cheeks as he showed off the bottle from his hands and said, "N-No, there's still a bit more wine in here."

"OH, I'M SORRY. I DIDN'T MEAN TO STARTLE YOU!"

"Don't fret over it. It was simply a surprise, is all."

Papyrus moved a bit closer to Gaster, shifting to stand next to him as Papyrus poured himself a small glass of wine. "SO, HAVE YOU BEEN ENJOYING THE PARTY? I COULDN'T HELP BUT NOTICE YOU'VE MOSTLY KEPT TO YOURSELF ALL NIGHT" he asked.

"Oh, don't worry. I am enjoying myself, it's just that I find it hard to be quite as sociable as you bunch," answered Gaster.

The younger skeleton slowly moved his gloved hand so that his index finger was lightly rubbing over the palm of Gaster's hand. This caused Gaster to jolt his head down as his breath hitched. When he looked back up, Papyrus was facing him again, only this time he seemed to have a more...suggestive look in his now half lidded eyes.

"WELL, DOCTOR, IF YOU FIND THE PARTY TO BE A BIT TO RAMBUNCTIOUS FOR YOUR TASTE," Papyrus glided his hand from Gaster's palm up his arm, to tentatively grab at his shoulder and begin to rub hit, grazing Gaster's neck with each circle, "THEN MAYBE I COULD...ENTERTAIN YOU SOMEWHERE MORE PRIVATE?"

Gaster's face flushed a color he didn't even know were possible as he stopped breathing. He swallowed the lump in his throat he hadn't noticed had formed. Papyrus' face was oh, so close to his own now. He could almost feel his breath on his own. Infact, from this angle Gaster could slightly see Papyrus' ribcage from underneath his dress.

"I-I, um, Papyrus, I-"

Papyrus quickly backed off and grabbed his own neck, looking a bit embarrassed as a light blush dusted across his face. "I-I KNOW, I CAME ON TOO STRONG, DID I NOT? I'M SORRY, I SHOULDN'T HAVE JUST DONE THAT-"

"No!" Gaster interrupted Papyrus, grabbing at the younger's hand. Papyrus looked at Gaster with hesitant eyes as he saw the flushed scientist tighten his grip on his own.

"Papyrus, you didn't do anything wrong. The truth is is that I, well, have been very interested in you for a while. I just was...surprised you made a move this forward. Not that I'm against it! I just wouldn't have expected it from you," Gaster reassured, giving Papyrus a warm smile and interlacing his fingers with Papyrus'.

Papyrus' eyes slightly widened, and then his face twisted into a smug smile and looked at Gaster with a sultry gaze. He pressed his chest up against Gaster's, heating up Gaster's body with a longing buzz. He raised a gloved hand and caressed the side of Gaster's jaw.

"YOU KNOW, DOCTOR. THERE ARE A _LOT_ OF THINGS I CAN DO THAT YOU WOULDN'T EXPECT OF ME."

Gaster found himself biting his lip as he instinctively pushed his groin against Papyrus'. He could feel his member rising as he took in Papyrus' words. Gaster reached around and grabbed Papyrus' behind, bunching up his skirt as he ground against Papyrus.

"Oh really, Papyrus?" Gaster whispered softly. He then forcefully grabbed and pulled Papyrus in closer to him until the two were less than 2 inches apart. "Then is there a hidden reason you really wore this outfit tonight?"

Wrapping his arms around Gaster's neck, Papyrus tilted his head and replied, "WELL, I GUESS I _WAS_ TRYING TO CATCH YOUR ATTENTION, NOW WAS I?"

Gaster smirked. "Such a naughty little exhibistionist you are, Papyrus."

Gaster suddenly shivered as he felt a warm wetness glide across his neck, and he turned to Papyrus's head to see his now long and conjured tongue running along Gaster. "WELL AS YOUR MAID, I DO LIVE TO PLEASE~"

Gaster grabbed a rough hold of Papyrus' neck, causing Papyrus to gasp and blush deep orange. He groaned and laid his hand on top of Gaster's grasp and smiled.

With a sinister smirk, Gaster released his hold, resulting in a whimper from Papyrus, as he then held Papyrus' hand and led the skeleton down the hallway into the house's bathroom. Once inside, Gaster locked the door and lifted Papyrus up and propped him on top of the sink.

Gaster let his hands travel across Papyrus' body, going down further and further until his fingers grazed the bottom of his maid's dress, earning him small whines from the skeleton below him.

Slowly, Gaster lifted the skirt to reveal Papyrus' lacey, black underwear attached to his garter belt. Papyrus turned his head to the left and covered his blushing face at the exposure.

"Oh, so _now_ we're feeling shy, are we?" Gaster chuckled.

"P-PLEASE GASTER...TOUCH ME," Papyrus whispered softly into his hand, darting his pupils to Gaster. Papyrus' vision was met with the doctor's deep, intruding stare penetrating into his own.

"Do you want your master to kiss you down here?" Gaster growled, forcing Papyrus' hand away from his mouth and lightly grazing his fingers along his crotch.

Papyrus squirmed into the touch and desperately bucked his hips into Gaster's hands. When he did this, Gaster pulled his hand away from the area, causing the maid to whimper.

"Use your words darling."

"YES, PLEASE," Papyrus replied breathily, "PLEASE SIR, TOUCH ME THERE."

Gaster leaned down and planted a light kiss on Papyrus' face.

"As you wish, pet."

The doctor then bent down and led his face under Papyrus' dress and ducked underneath. Covered under the frills, the only thing in front of him was Papyrus' lace clad underwear, which was straining to maintain its shape due to the thick bulge protruding from under the cloth.

He slipped the undergarments off to reveal Papyrus' cock. It was long and had considerably good girth. Gaster's mouth watered just at the thought of wrapping his mouth around Papyrus' member. Licking his proverbial lips, Gaster began by gently trailing his tongue up the underside of his shaft.

"M-MMPH!" Gaster heard, the sound a bit muffled from where he was. From what it sounded like, Papyrus had covered his mouth again, most likely to prevent the rest of the party's attendants from overhearing what kind of party games the two were engaging in without them.

Gaster began trailing small kisses along the length of his cock, feeling the recipient's legs shudder the closer his mouth got to the tip. Gaster landed one final kiss on the tip of Papyrus' dick before he began engulfing his mouth around Papyrus.

"MMMPH! MM- OH F-FU-MMM-" Papyrus responded, trying to pay attention to his volume. There was nothing the receiving skeleton wanted more than to grab hold of Gaster's head and to thrust into his mouth, but Papyrus knew he had to hold back a bit in order to savor every minute of the process.

The older skeleton could feel the younger's legs squeeze tightly against his skull, holding his mouth in place. Gaster dived deeper into the position, gagging as he choked down more of Papyrus' length. He then bobbed his head back upwards, gasping for air. After taking a breath, let let himself begin to fall into a rhythm of engulfing Papyrus' cock in his mouth as he moved his head up and down and ran his tongue along his shaft.

Then, Gaster sucked the underside of skin beneath Papyrus' tip. From above, Papyrus shuddered heavily and groaned and Gaster felt Papyrus' hand clutch the top of his skull through the fabric of the dress. He suckled on the area harder, earning a hiss from Papyrus.

"SO...CLOSE, I-I CAN'T, _PLEASE_ DON'T STOP," Papyrus gasped.

Gaster kept sucking while taking his tongue and swirling it around the tip. Papyrus' moans were slowly becoming louder and more muffled as Papyrus tried his best to contain his pleasure.

"D-DOCTOR, I'M GONNA-!" Papyrus tried to warn before forcefully thrusting his hips upwards, shoving his cock down Gaster's mouth as he came in his throat. Gaster's pupils rolled to the back of his skull as he felt Papyrus' load drip down his throat as choked and tried to swallow it all.

Finally, Papyrus lowered his hips, freeing Gaster of his hold. Gaster pulled his head out from underneath Papyrus' dress to reveal his own face to the maid, breathing heavily. He met Papyrus' half lidded gaze, pleasure drunk face.

"W-WELL, DOCTOR THAT WAS..._VERY_ ENJOYABLE," Papyrus said after a moment.

Gaster chuckled and closed in on Papyrus. He grabbed the younger's chin and forced him to make direct eye contact with himself.

"My dear, if you thought just a simple blowjob was good, just wait until _after_ the party~"

**Author's Note:**

> Happy Belated Halloween, thank you so much for reading! This is my first time seriously trying to write smut, so please comment any constructive criticism you might have. You can also expect some more Papyrus/Gaster stuff from me in the future ;)
> 
> The next update for All In This Together is being worked on!


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